1. Field of the Invention
The invention relates to an apparatus for checking semiconductor wafers.
In the production of integrated semiconductor circuits, the semiconductor wafers must be repeatedly checked for the proper characteristics. Defective semiconductor wafers need to be detected in the process, so that they can either be eliminated from the further course of production entirely or be suitably reworked before further production steps are performed on them and they are then returned to the normal course of production, on the condition that they are free of defects.
Checks of semiconductor wafers for perfect characteristics (for instance checking for freedom from particles, or in other words soil and deposits, checking for paint coatings applied, etc.) are known to be eminently important if good yields in the production process are to be attained.
Heretofore, such checks have been done manually, either with the aid of conventional microscopes or without a microscope, with oblique light. On one hand, that is very tiring for the worker, especially for his or her eyes and back (because of posture and long hours of sitting). On the other hand, it involves major uncertainties as well, since the worker's concentration on detecting defects and sorting out good and bad wafers diminishes over time.
2. Summary of the Invention
It is accordingly an object of the invention to provide an apparatus for checking semiconductor wafers, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known apparatuses of this general type and with the aid of which a checking process can be automated.
With the foregoing and other objects in view there is provided, in accordance with the invention, an apparatus for checking semiconductor wafers comprising a receiver for a semiconductor wafer to be checked; a light for illuminating the semiconductor wafer; a hemispherical hood having a surface and a hemispherical region defining an interior inside the hemispherical region; a further hood disposed in the vicinity of the light; a camera being disposed at the hemispherical hood and having a lens looking into the interior inside the hemispherical hood; and an evaluator being connected to the camera for controlling the camera and receiving, buffer-storing, processing and outputing data transmitted by the camera.
With the objects of the invention in view, there is also provided an apparatus for checking semiconductor wafers, comprising a receiver for a semiconductor wafer to be checked, the receiver having a center point; a first light for directly illuminating the semiconductor wafer with light of a first color; a second light for indirectly illuminating the semiconductor wafer with light of a second color being complementary to the first color; a hemispherical hood having a surface of the second color and having a hemispherical region defining an interior inside the hemispherical region; a further hood being disposed above the first light, being opaque to incident light, permitting the semiconductor wafer to be illuminated directly by the first light, and permitting the semiconductor wafer to only be illuminated indirectly by the second light; a first camera disposed at the hemispherical hood vertically above the center point of the receiver for the semiconductor wafer to be checked, the first camera having a lens looking into the interior and a filter admitting only light of the first color; a second camera being disposed at the hemispherical hood and having a lens looking into the interior and a filter admitting only light of the second color, the second camera being disposed at an angle greater than 0.degree. relative to the center point of the receiver for the semiconductor wafer to be checked; and an evaluator being connected to both of the cameras for controlling the cameras and for receiving, buffer-storing, further processing and outputing data transmitted from the cameras.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an apparatus for checking semiconductor wafers, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.